1. Field of the Invention
The present invention relates to a defluxing agent, a cleaning method and a cleaning apparatus, and especially it relates to a defluxing agent, cleaning method and cleaning apparatus for non-chlorine-type defluxing after soldering.
The production and use of chlorine-type organic solvents which deplete the ozone layer are recently being ever more regulated by the legislatures of participant nations to the Montreal Protocol. Since chlorine-type organic solvents have been used in the past as defluxing agents for cleaning flux after soldering, there has been a great acceleration in the development of defluxing agents which do not use chlorine-type organic solvents.
2. Description of the Related Art
During the production of electronic circuit parts by soldering, the post-solder flux has conventionally been cleaned for removal using 1,1,1-trichloroethane.
1,1,1-trichloroethane not only has a high ability to dissolve rosin, the main component of post-solder flux, but it also has a low toxicity and no inflammation point, giving it superior safety as a defluxing agent, and it has thus been indispensable for the cleaning of flux.
Since 1,1,1-trichloroethane is to be completely banned in 1996, from that time on the cleaning of post-solder flux during the production of electronic circuit parts by soldering will become more difficult, and because the long-term reliability of the electronic circuit components will be reduced as a result of corrosive substances contained in the flux, the development of a substitute defluxing agent for 1,1,1-trichloroethane has become an urgent issue.
With the prolonged heating during soldering the acid components of the rosin contained in the flux react with the solder to cause chemical reactions such as the production of salts (metal carboxylic acid salts), etc., thus becoming insoluble to the solvent, and therefore the substitute defluxing agent for 1,1,1-trichloroethane must not simply dissolve the rosin prior to heating but must also dissolve the altered flux components which have reacted due to heat.
Nevertheless, because in the past most research has centered on chlorine-type solvents such as 1,1,1-trichloroethane, no non-chlorine-type solvents which dissolve heat-altered flux have been known.